Istanbul (other names) is Turkey's most populous city, and its cultural, and economic centre. It is located on the Bosphorus strait, and encompasses the natural harbor known as the Golden Horn (Turkish: HaliÁ), in the northwest of the country. Istanbul extends both on the European (Thrace) and on the Asian (Anatolia) side of the Bosphorus, and is thereby the only metropolis in the world which geographically is situated on two continents. Istanbul became the third capital of the Ottoman Empire (1290-1922) in 1453. Today, Istanbul is the industrial center of Turkey. Many of Turkey's major manufacturing plants are located in the city. Istanbul and its surrounding province produce cotton, fruit, olive oil, silk, and tobacco. Food processing, textile production, oil products, rubber, metal ware, leather, chemicals, electronics, glass, machinery, paper and paper products and alcoholic drinks are among the city's major industrial products. The city also has plants that assemble automobiles and trucks.Both Turkish and international investors have made Istanbul an important commercial metropolis. One of the most important industries is tourism: there are a large number of hotels in Istanbul catering to tourists and visiting professionals.